The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry (PIV) and the hot-wire anem...The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry (PIV) and the hot-wire anemometer are utilized to measure the flowfields and the velocity profiles of the actuator with different actuating factors. Analytical results show that pairs of counter-rotating vortices are generated near the nozzle. With the development of the synthetic ject, the synthetic jet rapidly spreads in the slot-width direction; while in the slot-length direction, it contracts firstly and slowly spreads. The centerline velocity distribution has a up-down tendency varying with axial distances, and accelerates to its maximum at z/b= 10. The transverse velocity profile across the slot-width is centro-symmetric and self-similar. However, the velocity profiles across the slot-length are saddle-like near the nozzle. It shows that there are two resonance frequencies for the actuator. If the actuator works with the resonance frequency, the vorticity and the velocity of the synthetic jet are higher than those of other frequencies. Compared with the continuous jet, the synthetic jet shows special flow characteristics.展开更多
Application of particle image velocity (PIV) techniques for measuringparticle size distribution and total number in an activation chamber of desulfurization system isintroduced. Watersheld algorithm is used to choose ...Application of particle image velocity (PIV) techniques for measuringparticle size distribution and total number in an activation chamber of desulfurization system isintroduced. Watersheld algorithm is used to choose the suitable initial gray level threshold whichis used to change the gray level images taken by PIV to black and white ones, then every particle inan image is isolated totally. For every isolating particle, its contour is tracked by the edgeenhancement filter function and kept by Freeman s chain code. Based on a set of particle s chincode, its size and size distribution are calculated and sorted. Finally, the experimental data ofcalcium particles and water drops, separately injected into the activation chamber, and the erroranalysis of data are given out.展开更多
This study was performed to investigate the effects of the cyclonic separation mechanism on the removal of magnesium from phosphate ore. An analysis of the particle-bubble collision mechanism in a cyclonic force field...This study was performed to investigate the effects of the cyclonic separation mechanism on the removal of magnesium from phosphate ore. An analysis of the particle-bubble collision mechanism in a cyclonic force field was used to design two different pulp circulation systems for a cyclonic-static micro-bubble flotation column (FCSMC). Experiments comparing the two conditions were then conducted. Size analysis of the feed and separated products was conducted with a BXF cyclone size analyzer. The results show that about 34.60% of the total MgO content in the feed exists in the -10 μm fraction. This demonstrates that magnesium removal from phosphate ore has the characteristics of a micro-fine particle flotation problem. Under conditions of cyclonic circulation the MgO level of the concentrate is 1.74g, which is lower than that obtained from the column operated in direct-flow circulation by 0.34%, These results indicate that the cyclonic circulation mechanism of the FCSMC can promote removal of micro-fine particles containing magnesium. This is attributed to the function of surface flotation and to the reduction of the lower separation limit under conditions of cyclonic circulation.展开更多
A model of magnetic stimulation is presented for analysis of the spatial distributions of the electric field induced by magnetic coils.Dimensionless analysis is introduced and makes the factors influencing the magnitu...A model of magnetic stimulation is presented for analysis of the spatial distributions of the electric field induced by magnetic coils.Dimensionless analysis is introduced and makes the factors influencing the magnitude of electric field into two parts:c (represents the stimulation conditions),and E 0 (reflects the geometry of coil).By 3 D simulation of the induced electric field of two kinds of coils,the effect of magnetic stimulation can be demonstrated and the factors influencing stimulating focality and depth are identified.The principles for determining the electric field magnitude,focality and magnetic stimulation depth when designing a reasonable coil and stimulator and achieving ideal stimulating effect are discussed.展开更多
The elemental composition,heat expansibility and breaking characteristics of limestone have been investigated with the use of an energy spectrum analyzer,a SEM,an optical microscope and an experimental heat swelling p...The elemental composition,heat expansibility and breaking characteristics of limestone have been investigated with the use of an energy spectrum analyzer,a SEM,an optical microscope and an experimental heat swelling power system.The results show that 1) the heat expansibility of limestone has anisotropic properties,and 2) the heat expansion rate in the direction perpendicular to stratification is eight times greater than the rate parallel to stratification.The changes in heat expansibility as a function of heating temperature is essentially coincident with that of swelling and breaking of mineral particles and the appearance of cracks,indicating that the reason for causing the heat expansion of rock are the structural changes of limestone caused by thermal stress,crystal transformation and mineral decomposition.The apparent destruction of limestone under high temperatures is largely characterized by rock stratification breaks.When the limestone is heated beyond a certain limit,the rock destroys into crazed cracks.展开更多
The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was ...The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was also performed to explain possible effects. From particle size analysis and strength tests, it is hypothesized that the strength of the soil is increased with the addition of certain salinity concentrations until there are reversed effects, which is between 20 g/L and 50 g/L from our study. The increase of strength is suggested to be the affect of a greater variety of particle sizes. Since NaCI plays a role in the particle size distribution, it also plays a role in the strength of soils. The degree of the effect of the water content also differs from concentrations, and could be due to the variation of hydration film thickness on particles, which is affected by the ions introduced from water.展开更多
Suspended sediment concentration(SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry,...Suspended sediment concentration(SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry, have been designed to measure in situ SSC and grain size distribution. But due to fund or other restrictions, many experiments were only conducted in laboratory, using an indoor laser grain-size analyzer and gravimetric method to measure grain size distribution and concentration, respectively. In this study the laboratory experiment is simplified by omitting the tiring step of gravimetric method. The connections between SSC and other parameters(obscuration, D50 and sorting index) were investigated based on 124 surface sediment samples collected from different offshore areas. A new method is developed for determining SSC in laboratory using a laser grain-size analyzer.展开更多
Background:Trampolining is a form of gymnastics that has increased in popularity over the last decade and due to its concurrence with the formative years of bone development,it may have an important impact on bone he...Background:Trampolining is a form of gymnastics that has increased in popularity over the last decade and due to its concurrence with the formative years of bone development,it may have an important impact on bone health.However,bone density,microarchitecture,and bone strength of competitive trampolinists have not been explored.Therefore,the purpose of this cross-sectional study was to investigate the relationship between trampolining participation and(1) bone density,area,and microarchitecture;and(2) estimated bone strength and the role of muscle and impact loading in young female adults.Methods:We recruited 29 female participants aged 16–29 years for this study(n=14 trampolinists;n=15 controls).Skeletal parameters were assessed using dual X-ray absorptiometry,high-resolution peripheral quantitative computed tomography(HR-pQCT),and finit element analysis(FEA).Muscle strength was measured using dynamometers.Results:Trampolinists had higher bone density at the hip and spine,greater trabecular density and thicker trabeculae at the tibia,as well as larger bones at both the tibia and radius than controls(p〈0.05).Trampolinists also had higher muscle strength than controls at the lower body with no difference between groups in the upper body.Estimates of bone strength using FEA were greater for trampolinists than controls at both the radius and tibia.Conclusion:This is the firs study to investigate bone density,area,and microarchitecture in female trampolinists using HR-p QCT.Trampolinists had greater bone density,area,microarchitecture,and estimated bone strength than controls.展开更多
The first modem survey of the Dead Sea was performed by the Geological Survey of Israel in 1959-1960, and the report published remains the baseline study for our understanding of the physical and chemical properties o...The first modem survey of the Dead Sea was performed by the Geological Survey of Israel in 1959-1960, and the report published remains the baseline study for our understanding of the physical and chemical properties of the lake. At the time the Dead Sea was a meromictic lake with a strong salinity gradient separating the deep waters (〉40 m depth) from the less saline surface waters. A few results of analyses of deeper water samples collected in the 1930s were reported, but overall we have very little information about the structure of the lake's water column before the 1959-1960 survey. However, it is little known that data on the physical and the chemical structure of the Dead Sea water column were obtained already in the middle of the 19~ century, and the information collected then is highly relevant for the reconstruction of the limnological properties of the lake in earlier times. The expedition of Lieutenant William Lynch (U.S. Navy) in 1848 reported the presence of a temperature minimum at a depth of-18 m, and also retrieved a water sample collected close to the bottom for chemical analysis. In 1864, the French Dead Sea exploration by the Duc de Luynes and his crew yielded detailed density and salinity profiles for a number of sampling stations. The results of these pioneering studies are discussed here, as well as the sampling equipment and measuring instruments used by the 1848 and the 1864 expeditions.展开更多
Super gravity field was employed to enhance electrolytic reaction for the preparation of copper powders.The morphology, microstructure and size of copper powders were characterized by scanning electron microscopy,X-ra...Super gravity field was employed to enhance electrolytic reaction for the preparation of copper powders.The morphology, microstructure and size of copper powders were characterized by scanning electron microscopy,X-ray diffractometry and laser particle analysis.The results indicated that current efficiencies of electrolytic copper powders under super gravity field increased by more than 20% compared with that under normal gravity condition.Cell voltage under super gravity field was also much lower.The size of copper powders decreased with the increase of gravity coefficient(G).The increase of current efficiency can be contributed to the disturbance of electrode/electrolyte interface and enhanced mass transfer of Cu2+ in super gravity field.Meanwhile,the huge gravity acceleration would promote the detachment of copper powders from electrode surface during electrolytic process,which can prevent the growth of copper powders.展开更多
This paper thoroughly studies the'. process of obtaining sulfur nanoparticles in aqueous medium from sodium polysulfide. Nanosize sulfur particles with orthorhombic structure were obtained at room temperature by mixi...This paper thoroughly studies the'. process of obtaining sulfur nanoparticles in aqueous medium from sodium polysulfide. Nanosize sulfur particles with orthorhombic structure were obtained at room temperature by mixing sodium polysulfide aqueous solution with various inorganic and organic acids. Sulfur nanoparticles were characterized by laser particle-size analyzer, X-ray diffraction, electron probe microscopy. Size of sulfur nanoparticles in aqueous dispersion is affected ;trongly by acid concentration, as well as nature of alcohols, used as wetting agents when measuring sulfur particles size iin aqueous medium. Availability of obtaining sulfur nanoparticles of 22-25 nm average si;,e in aqueous medium was revealed. High biological activity of sulfur nanoparticles and ethylalcohol composition on wheat grain couching was established.展开更多
The Rutherford backscattering (RBS) spectra of N+-implanted GaAs are measured with a He+ ion beam of 2.1MeV. The backscattering yield along 【 100 】 aligned incidence increases with the increase in implanted doses. T...The Rutherford backscattering (RBS) spectra of N+-implanted GaAs are measured with a He+ ion beam of 2.1MeV. The backscattering yield along 【 100 】 aligned incidence increases with the increase in implanted doses. The depth profiles of nitrogen and arsenic are measured by secondary ion mass spectrometer (SIMS).The diffusion of nitrogen in the implanted layers is explained as interstitial migration. The damage is very severe during the ion implantation, and it can be recovered psrtly by annealing. The two-step annealing improves the effect obviously. The calculstion on distribution of damage shows that the recovery is proceeded from the inner side to the surface during the annealing. The mechanism of damage is discussed briefly.展开更多
The dispersibility of vermiculite is the key factor that affects the application of vermiculite.In this paper,the milled natural vermiculite was pillared by organic quaternary ammonium salts.Then the pillared vermicul...The dispersibility of vermiculite is the key factor that affects the application of vermiculite.In this paper,the milled natural vermiculite was pillared by organic quaternary ammonium salts.Then the pillared vermiculite was ground and homogenized under the existence of dispersive agent to form a stable vermiculite hydrosol system.Small angle X-ray diffraction(SA-XRD),fourier transform infrared spectroscopy(FTIR),and thermogravimetric analyses(TGA)were used to characterize the structure and thermal property of the vermiculite.The results indicate that the exfoliated vermiculite is successfully obtained.The analyses of laser particle size analyzer,transmission electron microscope(TEM),and Tyndall phenomenon analyzer demonstrate that the vermiculite hydrosol prepared is a stable hydrosol system.展开更多
Objective To establish the normal measurements of diameter of extraocular muscles (EOMs) by multislice computed tomography (CT). Methods Orbits of 50 volunteers (25 male and 25 female) were scanned with a multislice C...Objective To establish the normal measurements of diameter of extraocular muscles (EOMs) by multislice computed tomography (CT). Methods Orbits of 50 volunteers (25 male and 25 female) were scanned with a multislice CT scanner. For each subject, one axial image at the central level of the eyeball, one coronal image about 1 cm behind globe, and two oblique sagittal images respectively along the left and right optic nerve were used for measurements of the thickness and width of EOMs. The statistic significance of measurement value between male and female and between left and right eyes was evaluated. Results There were no significant differences in the thickness and width of superior muscle group, lateral rectus, medial rectus, lateral rectus, superior oblique, inferior oblique and the thickness of levator palpebrae superioris between the left and right eyes as well as between male and female groups (all P>0.05). The thickness of superior muscle group and inferior rectus had not significant difference (2.9±0.7 vs. 3.3±0.8 mm, P=0.162), while the thickness of medial rectus was significantly higher than that of lateral rectus (3.1±0.5 vs. 2.2±0.6 mm, P=0.000). Conclusions The CT measurement of extraocular musculature is simple and time-saving and can be applied in the clinical work. The normative data obtained may be useful in determining pathologic enlargement of the EOMs in both thyroid-associated orbitopathy patients and other various orbital conditions.展开更多
Edible insects, escamoles ant eggs of the Formicidae family are consumed by cultural tradition at rural communities and by sensory characteristics at high class restaurants of Mexico; however, people ignore the import...Edible insects, escamoles ant eggs of the Formicidae family are consumed by cultural tradition at rural communities and by sensory characteristics at high class restaurants of Mexico; however, people ignore the importance of insect consumption in the nutrition of humans. Laboratory spectroscopy methods in food analysis represent benefits in time and precision. The aim of this study is to assess macronutrients and micronutrients of escamoles and eggs by spectroscopic methods to inform population the benefits they provide in health and to mention the advantage in the use of these techniques at laboratory work. Samples were gather the second week of March and April 2012, at Hidalgo State and analyze moisture and macronutrients by AOAC (Association of Official Analytical Chemistry) methods, amino acids by cation exchange chromatography, tryptophan was determined by a colorimeter method, fatty acids by GC (gas chromatography) using helium as a carrier (AOAC), fat soluble vitamins A, D and E by HPLC (high performance liquid chromatography), and minerals by atomic absorption spectrophotometers and phosphorus by colorimeter (AOAC). Data showed high amount in proteins, lipids and minerals; low in fiber and soluble carbohydrates; contained all essential amino acids. Fatty acids contain monounsaturated and polyunsaturated. Fat soluble vitamins A, D and E. Minerals: sodium, phosphorus, potassium, magnesium, calcium and manganese. Escamoles ant eggs include polyunsaturated fatty acids essential for mental development, vitamin A to prevent eye diseases, vitamin E as antioxidant and vitamin D involved in calcium absorption that low intake, impair grow and bone health. Iron and zinc contained anemia. Regarding the laboratory benefits, needs less expensive chemicals, testing is clean, rapid and easy results of multiple samples, but it is required to handle by qualified chemists. In conclusion, data may change according to biotic and abiotic conditions of the environment; however, escamoles have all nutrients in adequate balance to improve human health; and provide faster and precise results.展开更多
文摘The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry (PIV) and the hot-wire anemometer are utilized to measure the flowfields and the velocity profiles of the actuator with different actuating factors. Analytical results show that pairs of counter-rotating vortices are generated near the nozzle. With the development of the synthetic ject, the synthetic jet rapidly spreads in the slot-width direction; while in the slot-length direction, it contracts firstly and slowly spreads. The centerline velocity distribution has a up-down tendency varying with axial distances, and accelerates to its maximum at z/b= 10. The transverse velocity profile across the slot-width is centro-symmetric and self-similar. However, the velocity profiles across the slot-length are saddle-like near the nozzle. It shows that there are two resonance frequencies for the actuator. If the actuator works with the resonance frequency, the vorticity and the velocity of the synthetic jet are higher than those of other frequencies. Compared with the continuous jet, the synthetic jet shows special flow characteristics.
基金The Special Funds for State Key Projects for Fun- damental Research (G1999022201-04).
文摘Application of particle image velocity (PIV) techniques for measuringparticle size distribution and total number in an activation chamber of desulfurization system isintroduced. Watersheld algorithm is used to choose the suitable initial gray level threshold whichis used to change the gray level images taken by PIV to black and white ones, then every particle inan image is isolated totally. For every isolating particle, its contour is tracked by the edgeenhancement filter function and kept by Freeman s chain code. Based on a set of particle s chincode, its size and size distribution are calculated and sorted. Finally, the experimental data ofcalcium particles and water drops, separately injected into the activation chamber, and the erroranalysis of data are given out.
基金supported by the National Key Technology R&D Program for the 11th Five-Year Plan of China(No. 2008BAB31B01)
文摘This study was performed to investigate the effects of the cyclonic separation mechanism on the removal of magnesium from phosphate ore. An analysis of the particle-bubble collision mechanism in a cyclonic force field was used to design two different pulp circulation systems for a cyclonic-static micro-bubble flotation column (FCSMC). Experiments comparing the two conditions were then conducted. Size analysis of the feed and separated products was conducted with a BXF cyclone size analyzer. The results show that about 34.60% of the total MgO content in the feed exists in the -10 μm fraction. This demonstrates that magnesium removal from phosphate ore has the characteristics of a micro-fine particle flotation problem. Under conditions of cyclonic circulation the MgO level of the concentrate is 1.74g, which is lower than that obtained from the column operated in direct-flow circulation by 0.34%, These results indicate that the cyclonic circulation mechanism of the FCSMC can promote removal of micro-fine particles containing magnesium. This is attributed to the function of surface flotation and to the reduction of the lower separation limit under conditions of cyclonic circulation.
文摘A model of magnetic stimulation is presented for analysis of the spatial distributions of the electric field induced by magnetic coils.Dimensionless analysis is introduced and makes the factors influencing the magnitude of electric field into two parts:c (represents the stimulation conditions),and E 0 (reflects the geometry of coil).By 3 D simulation of the induced electric field of two kinds of coils,the effect of magnetic stimulation can be demonstrated and the factors influencing stimulating focality and depth are identified.The principles for determining the electric field magnitude,focality and magnetic stimulation depth when designing a reasonable coil and stimulator and achieving ideal stimulating effect are discussed.
基金Project 50574037 supported by the National Natural Science Foundation of China
文摘The elemental composition,heat expansibility and breaking characteristics of limestone have been investigated with the use of an energy spectrum analyzer,a SEM,an optical microscope and an experimental heat swelling power system.The results show that 1) the heat expansibility of limestone has anisotropic properties,and 2) the heat expansion rate in the direction perpendicular to stratification is eight times greater than the rate parallel to stratification.The changes in heat expansibility as a function of heating temperature is essentially coincident with that of swelling and breaking of mineral particles and the appearance of cracks,indicating that the reason for causing the heat expansion of rock are the structural changes of limestone caused by thermal stress,crystal transformation and mineral decomposition.The apparent destruction of limestone under high temperatures is largely characterized by rock stratification breaks.When the limestone is heated beyond a certain limit,the rock destroys into crazed cracks.
基金Acknowledgements: This work was supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, SEM, China, and also supported by the United States National Science Foundation. The authors thank Prof. SHEN H. H. and Prof. SHEN H. T. from Clarkson University for their unconditional support to this work.
文摘The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was also performed to explain possible effects. From particle size analysis and strength tests, it is hypothesized that the strength of the soil is increased with the addition of certain salinity concentrations until there are reversed effects, which is between 20 g/L and 50 g/L from our study. The increase of strength is suggested to be the affect of a greater variety of particle sizes. Since NaCI plays a role in the particle size distribution, it also plays a role in the strength of soils. The degree of the effect of the water content also differs from concentrations, and could be due to the variation of hydration film thickness on particles, which is affected by the ions introduced from water.
基金sponsored by Marine Commonweal Scientific Research Foundation (201005009)
文摘Suspended sediment concentration(SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry, have been designed to measure in situ SSC and grain size distribution. But due to fund or other restrictions, many experiments were only conducted in laboratory, using an indoor laser grain-size analyzer and gravimetric method to measure grain size distribution and concentration, respectively. In this study the laboratory experiment is simplified by omitting the tiring step of gravimetric method. The connections between SSC and other parameters(obscuration, D50 and sorting index) were investigated based on 124 surface sediment samples collected from different offshore areas. A new method is developed for determining SSC in laboratory using a laser grain-size analyzer.
文摘Background:Trampolining is a form of gymnastics that has increased in popularity over the last decade and due to its concurrence with the formative years of bone development,it may have an important impact on bone health.However,bone density,microarchitecture,and bone strength of competitive trampolinists have not been explored.Therefore,the purpose of this cross-sectional study was to investigate the relationship between trampolining participation and(1) bone density,area,and microarchitecture;and(2) estimated bone strength and the role of muscle and impact loading in young female adults.Methods:We recruited 29 female participants aged 16–29 years for this study(n=14 trampolinists;n=15 controls).Skeletal parameters were assessed using dual X-ray absorptiometry,high-resolution peripheral quantitative computed tomography(HR-pQCT),and finit element analysis(FEA).Muscle strength was measured using dynamometers.Results:Trampolinists had higher bone density at the hip and spine,greater trabecular density and thicker trabeculae at the tibia,as well as larger bones at both the tibia and radius than controls(p〈0.05).Trampolinists also had higher muscle strength than controls at the lower body with no difference between groups in the upper body.Estimates of bone strength using FEA were greater for trampolinists than controls at both the radius and tibia.Conclusion:This is the firs study to investigate bone density,area,and microarchitecture in female trampolinists using HR-p QCT.Trampolinists had greater bone density,area,microarchitecture,and estimated bone strength than controls.
文摘The first modem survey of the Dead Sea was performed by the Geological Survey of Israel in 1959-1960, and the report published remains the baseline study for our understanding of the physical and chemical properties of the lake. At the time the Dead Sea was a meromictic lake with a strong salinity gradient separating the deep waters (〉40 m depth) from the less saline surface waters. A few results of analyses of deeper water samples collected in the 1930s were reported, but overall we have very little information about the structure of the lake's water column before the 1959-1960 survey. However, it is little known that data on the physical and the chemical structure of the Dead Sea water column were obtained already in the middle of the 19~ century, and the information collected then is highly relevant for the reconstruction of the limnological properties of the lake in earlier times. The expedition of Lieutenant William Lynch (U.S. Navy) in 1848 reported the presence of a temperature minimum at a depth of-18 m, and also retrieved a water sample collected close to the bottom for chemical analysis. In 1864, the French Dead Sea exploration by the Duc de Luynes and his crew yielded detailed density and salinity profiles for a number of sampling stations. The results of these pioneering studies are discussed here, as well as the sampling equipment and measuring instruments used by the 1848 and the 1864 expeditions.
基金Projects(50804043, 50674011) supported by the National Natural Science Foundation of ChinaProject(KZCX2-YW-412-2) supported the Knowledge Innovation Program of Chinese Academy of Sciences
文摘Super gravity field was employed to enhance electrolytic reaction for the preparation of copper powders.The morphology, microstructure and size of copper powders were characterized by scanning electron microscopy,X-ray diffractometry and laser particle analysis.The results indicated that current efficiencies of electrolytic copper powders under super gravity field increased by more than 20% compared with that under normal gravity condition.Cell voltage under super gravity field was also much lower.The size of copper powders decreased with the increase of gravity coefficient(G).The increase of current efficiency can be contributed to the disturbance of electrode/electrolyte interface and enhanced mass transfer of Cu2+ in super gravity field.Meanwhile,the huge gravity acceleration would promote the detachment of copper powders from electrode surface during electrolytic process,which can prevent the growth of copper powders.
文摘This paper thoroughly studies the'. process of obtaining sulfur nanoparticles in aqueous medium from sodium polysulfide. Nanosize sulfur particles with orthorhombic structure were obtained at room temperature by mixing sodium polysulfide aqueous solution with various inorganic and organic acids. Sulfur nanoparticles were characterized by laser particle-size analyzer, X-ray diffraction, electron probe microscopy. Size of sulfur nanoparticles in aqueous dispersion is affected ;trongly by acid concentration, as well as nature of alcohols, used as wetting agents when measuring sulfur particles size iin aqueous medium. Availability of obtaining sulfur nanoparticles of 22-25 nm average si;,e in aqueous medium was revealed. High biological activity of sulfur nanoparticles and ethylalcohol composition on wheat grain couching was established.
文摘The Rutherford backscattering (RBS) spectra of N+-implanted GaAs are measured with a He+ ion beam of 2.1MeV. The backscattering yield along 【 100 】 aligned incidence increases with the increase in implanted doses. The depth profiles of nitrogen and arsenic are measured by secondary ion mass spectrometer (SIMS).The diffusion of nitrogen in the implanted layers is explained as interstitial migration. The damage is very severe during the ion implantation, and it can be recovered psrtly by annealing. The two-step annealing improves the effect obviously. The calculstion on distribution of damage shows that the recovery is proceeded from the inner side to the surface during the annealing. The mechanism of damage is discussed briefly.
基金National High Technology Research and Development Program(863 Program),China(No.2007AA03Z336)Program for New Century Excellent Talents in University,China(No.NCET-07-0174)
文摘The dispersibility of vermiculite is the key factor that affects the application of vermiculite.In this paper,the milled natural vermiculite was pillared by organic quaternary ammonium salts.Then the pillared vermiculite was ground and homogenized under the existence of dispersive agent to form a stable vermiculite hydrosol system.Small angle X-ray diffraction(SA-XRD),fourier transform infrared spectroscopy(FTIR),and thermogravimetric analyses(TGA)were used to characterize the structure and thermal property of the vermiculite.The results indicate that the exfoliated vermiculite is successfully obtained.The analyses of laser particle size analyzer,transmission electron microscope(TEM),and Tyndall phenomenon analyzer demonstrate that the vermiculite hydrosol prepared is a stable hydrosol system.
文摘Objective To establish the normal measurements of diameter of extraocular muscles (EOMs) by multislice computed tomography (CT). Methods Orbits of 50 volunteers (25 male and 25 female) were scanned with a multislice CT scanner. For each subject, one axial image at the central level of the eyeball, one coronal image about 1 cm behind globe, and two oblique sagittal images respectively along the left and right optic nerve were used for measurements of the thickness and width of EOMs. The statistic significance of measurement value between male and female and between left and right eyes was evaluated. Results There were no significant differences in the thickness and width of superior muscle group, lateral rectus, medial rectus, lateral rectus, superior oblique, inferior oblique and the thickness of levator palpebrae superioris between the left and right eyes as well as between male and female groups (all P>0.05). The thickness of superior muscle group and inferior rectus had not significant difference (2.9±0.7 vs. 3.3±0.8 mm, P=0.162), while the thickness of medial rectus was significantly higher than that of lateral rectus (3.1±0.5 vs. 2.2±0.6 mm, P=0.000). Conclusions The CT measurement of extraocular musculature is simple and time-saving and can be applied in the clinical work. The normative data obtained may be useful in determining pathologic enlargement of the EOMs in both thyroid-associated orbitopathy patients and other various orbital conditions.
文摘Edible insects, escamoles ant eggs of the Formicidae family are consumed by cultural tradition at rural communities and by sensory characteristics at high class restaurants of Mexico; however, people ignore the importance of insect consumption in the nutrition of humans. Laboratory spectroscopy methods in food analysis represent benefits in time and precision. The aim of this study is to assess macronutrients and micronutrients of escamoles and eggs by spectroscopic methods to inform population the benefits they provide in health and to mention the advantage in the use of these techniques at laboratory work. Samples were gather the second week of March and April 2012, at Hidalgo State and analyze moisture and macronutrients by AOAC (Association of Official Analytical Chemistry) methods, amino acids by cation exchange chromatography, tryptophan was determined by a colorimeter method, fatty acids by GC (gas chromatography) using helium as a carrier (AOAC), fat soluble vitamins A, D and E by HPLC (high performance liquid chromatography), and minerals by atomic absorption spectrophotometers and phosphorus by colorimeter (AOAC). Data showed high amount in proteins, lipids and minerals; low in fiber and soluble carbohydrates; contained all essential amino acids. Fatty acids contain monounsaturated and polyunsaturated. Fat soluble vitamins A, D and E. Minerals: sodium, phosphorus, potassium, magnesium, calcium and manganese. Escamoles ant eggs include polyunsaturated fatty acids essential for mental development, vitamin A to prevent eye diseases, vitamin E as antioxidant and vitamin D involved in calcium absorption that low intake, impair grow and bone health. Iron and zinc contained anemia. Regarding the laboratory benefits, needs less expensive chemicals, testing is clean, rapid and easy results of multiple samples, but it is required to handle by qualified chemists. In conclusion, data may change according to biotic and abiotic conditions of the environment; however, escamoles have all nutrients in adequate balance to improve human health; and provide faster and precise results.